Black-backed Bittern

The species measures from 25 to 36 cm (9.8 to 14.2 in), has a total weight of 60–120 g (2.1–4.2 oz), averaging 84 g (3.0 oz). This is a very small bittern and one of the smallest herons in the world. The adult male has largely black upperparts, including a black cap, while the underparts, as well as the neck, breast and the sides of the head, are rich chestnut. There are large buff patches on the shoulders, conspicuous in flight. The female is duller, brown and streaked on back and crown; immature birds are similar. Voice: Vocalisations of the bittern are poorly known. Outside the breeding season the birds are usually silent, though they may utter a small range of low croaking or grunting sounds. During the breeding season the advertising call, a deep, low and monotonous croaking call, repeated at half-second intervals and said to be made only by the males, may be heard.